Disc-shaped recording medium disc driving device and method and apparatus for producing disc

ABSTRACT

The information such as address is to be efficiently formed into wobble components and further the S/N ratio in reproducing the information formed into the wobble components is to be improved. In an optical disc of the present invention, there are recorded in a wobble the address information modulated in accordance with the MSK (minimum shift keying) system and the address information modulated in accordance with a modulation system in which even harmonics signals are added to a sinusoidal carrier signal and in which the polarity of the harmonics signal is changed depending on the sign of the data for modulation.

TECHNICAL FIELD

[0001] This invention relates to a disc-shaped recording medium, havinga land and/or a groove formed thereon in a circling fashion foroperating as a recording track formed in a meandering fashion in meetingwith the wobble signal, a disc driving device for recording and/orreproducing data for this disc-shaped recording medium, and to a methodand apparatus for producing this disc-shaped recording medium.

BACKGROUND ART

[0002] Up to now, an optical disc having a guide groove, termed circlinga pre-groove, has been known. If this pre-groove is formed, the grooveand/or the land (area sandwiched between neighboring turns of thegroove) becomes a recording track. By this pre-groove, formed in theoptical disc, the disc driving side, responsible for recording and/orreproduction, is able to detect components of both edges of therecording track from the reflected laser light to effect servo controlso that the laser light will be illuminated centrally of the two edges.

[0003] There has so far been known an optical disc in which thepre-groove is caused to meander in meeting with the wobble signalcorresponding to FM modulated or PSK modulated carrier signal. In themodulating components of the wobble signal, there is contained e.g., thephysical address information of the recording track at the recordingpositions of the wobble signal. So, the disc driving side, responsiblefor recording and/or reproduction, is able to detect the wobble signalfrom signals representing fluctuating components of both edges of therecording tracks (so-called push-pull signals) to demodulate the addressinformation contained in the wobble signal to perform address control ofthe recording and/or reproducing positions.

[0004] However, with the system of inserting e.g., the addressinformation into the wobble signal corresponding to the FM modulatedcarrier signals, a problem is raised that address reproductioncharacteristics are deteriorated by cross-talk components fromneighboring tracks. In the system of inserting e.g., the addressinformation into the wobble signal by PSK modulating the carrier signal,there is raised a problem that higher harmonics at the phase changepoints are superimposed on the playback signals to deterioratereproduction characteristics. Moreover, in the case of the PSKmodulation, the higher harmonics components are contained, with theresult that the circuit configuration of the wobble signal demodulatingcircuit becomes complicated.

DISCLOSURE OF THE INVENTION

[0005] It is therefore an object of the present invention to provide adisc-shaped recording medium having the information such as addressinformation formed efficiently into the wobble components, and in whichthe S/N ratio may be improved in reproducing the information containedin the wobble components, a disc driving device for recording and/orreproducing data for this disc-shaped recording medium, and a method andapparatus for producing this disc-shaped recording medium.

[0006] For accomplishing the above object, the present inventionprovides a disc-shaped recording medium having a land and/or a grooveformed thereon in a circling fashion for operating as a recording track,the recording track meandering depending on a wobble signal, wherein

[0007] the wobble signal comprises

[0008] a first digital information MSK modulated using a firstsinusoidal signal of a predetermined frequency and using a secondsinusoidal signal of a frequency different from the predeterminedfrequency, and

[0009] a second digital information modulated onto a sinusoidal carriersignal by adding even harmonics signals to the sinusoidal carrier signaland by changing the polarity of the harmonics signals according to thesecond digital information (HMW modulated).

[0010] In another aspect, the present invention provides a disc-shapedrecording medium having a land and/or a groove formed thereon in acircling fashion for operating as a recording track, the recording trackmeandering depending on a wobble signal, wherein

[0011] an address unit with the address information stated therein isformed in the wobble signal as a predetermined data unit, the addressinformation comprising at least an address of the recording track,

[0012] the address unit is constructed to include at least one bit blockrepresenting bits forming the address information, and

[0013] the at least one block is formed in a waveform comprising apredetermined number of consecutive periods of a sinusoidal carriersignal by inserting a first bit string MSK modulated using thesinusoidal carrier signal and using a further sinusoidal signal of afrequency different from a frequency of the sinusoidal carrier signal,and a second bit string modulated onto the sinusoidal carrier signal byadding even harmonics signals to the sinusoidal carrier signal and bychanging the polarity of the harmonics signals according to the secondbit string (HMW modulated).

[0014] The present invention also provides a disc driving device forrecording and/or reproducing a disc-shaped recording medium, having aland and/or a groove formed thereon in a circling fashion for operatingas a recording track, the recording track meandering depending on awobble signal, the disc driving device comprising:

[0015] wobble information demodulating means for reproducing the wobblesignal from the disc-shaped recording medium and for demodulating thewobble signal to retrieve the digital information contained in thewobble signal;

[0016] wherein the wobble information demodulating means includes:

[0017] a first demodulating unit for retrieving the first digitalinformation which is MSK modulated using a first sinusoidal signal of apredetermined frequency and using a sinusoidal signal of a frequencydifferent from the predetermined frequency of the first sinusoidalsignal; and

[0018] a second demodulating unit for retrieving the second digitalinformation which is modulated onto a sinusoidal carrier signal byadding even harmonics signals to the sinusoidal carrier signal and bychanging the polarity of the harmonics signals according to the: seconddigital information (HMW modulated).

[0019] The present invention also provides an apparatus formanufacturing a disc-shaped recording medium by forming a land and/or agroove in a circling fashion on a surface of a master disc of adisc-shaped recording medium, the apparatus comprising:

[0020] means for forming the land and/or groove in a meandering fashiondepending on a wobble signal including

[0021] a first digital information MSK modulated using a firstsinusoidal signal of a predetermined frequency and using a secondsinusoidal signal of a frequency different from the predeterminedfrequency of the first sinusoidal signal, and

[0022] a second digital information modulated onto a sinusoidal carriersignal by adding even harmonics signals to the sinusoidal carrier signaland by changing the polarity of the harmonics signals according to thesecond digital information (HMW modulated).

[0023] In yet another aspect, the present invention provides a methodfor manufacturing a disc-shaped recording medium by forming a landand/or a groove in a circling fashion on a surface of a master disc of adisc-shaped recording medium, the method comprising the step of:

[0024] forming the land and/or groove in a meandering fashion dependingon a wobble signal including

[0025] a first digital information MSK modulated using a firstsinusoidal signal of a predetermined frequency and using a secondsinusoidal signal of a frequency different from the predeterminedfrequency of the first sinusoidal signal, and

[0026] a second digital information modulated onto a sinusoidal carriersignal by adding even harmonics signals to the sinusoidal carrier signaland by changing the polarity of the harmonics signals according to thesecond digital information (HMW modulated).

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 shows a track configuration of an optical disc embodyingthe present invention.

[0028]FIG. 2 shows a meandering state of the grooves.

[0029]FIG. 3 shows the MSK- and HMW modulated wobble signal.

[0030]FIGS. 4A to 4E illustrate MSK modulation.

[0031]FIG. 5 shows an MSK demodulation circuit for demodulating MSKmodulated wobble signals.

[0032]FIG. 6 shows an input wobble signal (MSK stream) and asynchronous-detected output signal (MSK×cos(ωt)) of the wobble signal.

[0033]FIG. 7 shows an integrated output value of the synchronousdetection output signal of the MSK stream, a hold value of theintegrated output value and data for modulation obtained on MSKdemodulation.

[0034]FIGS. 8A to 8C illustrate HMW modulation.

[0035]FIG. 9 shows a HMW demodulation circuit for demodulating HMWmodulated wobble signal.

[0036]FIG. 10 shows a reference carrier signals (cos(ωt)), a data string“1010” as data for modulation and a signal waveform of second harmonics(±sin(2ωt), −12 dB) generated in meeting with the data for modulation.

[0037]FIG. 11 shows the generated wobble signal (HMW stream).

[0038]FIGS. 12A and 12B illustrate a synchronous-detected output signalof an HMW stream (HMW×sin(2ωt)), an integrated output value of thesynchronous-detected output signal, a sample-held value of theintegrated output value and HMW data for modulation.

[0039]FIG. 13 shows an error correction block of a DVR disc embodyingthe present invention.

[0040]FIG. 14 shows an ECC cluster of the DVR disc.

[0041]FIG. 15 shows the relationship between a recording and/orreproducing cluster (RUB) and an address unit of the DVR disc.

[0042]FIG. 16 shows a bit block forming the address unit.

[0043]FIG. 17 shows a bit structure of a sync part in the address unit.

[0044]FIGS. 18A and 18B show a signal waveform of a monotone bit in thesync part and data for modulation

[0045]FIGS. 19A and 19B show a signal waveform of a first sync bit inthe sync part and data for modulation.

[0046]FIGS. 20A and 20B show a signal waveform of a second sync bit inthe sync part and data for modulation.

[0047]FIGS. 21A and 21B show a signal waveform of a third sync bit inthe first sync part and data for modulation.

[0048]FIGS. 22A and 22B show a signal waveform of a fourth sync bit inthe first sync part and data for modulation.

[0049]FIG. 23 shows a bit structure of a data part in the address unit.

[0050]FIGS. 24A to 24C show a signal waveform of an ADIP bitrepresenting bit “1” in the data part and data for modulation.

[0051]FIGS. 25A to 25C show a signal waveform of an ADIP bitrepresenting bit “0” in the data part and data for modulation.

[0052]FIG. 26 shows an overall configuration of the format of theaddress unit.

[0053]FIG. 27 shows the contents of the address information representedby the ADIP bit.

[0054]FIG. 28 shows an error correction block of the addressinformation.

[0055]FIG. 29 shows an address demodulation circuit of the DVR disc.

[0056]FIGS. 30A to 30E show the control timing of the addressdemodulation circuit.

[0057]FIGS. 31A to 31C show a signal waveform on HMW demodulation of theADIP bit with the code contents of “1” by the address demodulationcircuit.

[0058]FIGS. 32A to 32C show a signal waveform on HMW demodulation of theADIP bit with the code contents of “1” by the address demodulationcircuit.

[0059]FIG. 33 shows a block structure of an optical disc drive embodyingthe present invention.

[0060]FIG. 34 shows the structure of a cutting device for an opticalmaster disc embodying the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0061] The wobbling system for an optical disc, an optical disc drivefor recording and/or reproducing data on or from the optical disc, and amethod for producing the optical disc, according to the presentinvention, are now explained in detail.

[0062] 1. Wobbling System for Optical Disc

[0063] 1-1 Overall Explanation of the Wobbling System

[0064] In an optical disc according to an embodiment of the presentinvention, a groove GV, operating as a recording track, is formed, asshown in FIG. 1. This groove GV is formed spirally from the inner rimtowards the outer rim of the disc. Thus, when seen in a radialcross-section, the optical disc has a convex-shaped land L and arecessed groove GV, in alternation with one another, as shown in FIG. 2.

[0065] The groove GV of the optical disc 1 is formed meandering relativeto the tangential direction thereof, as shown in FIG. 2. The meanderingshape of the groove GV is in meeting with the wobbling signal. So, withthe optical disc drive, both edge positions of the groove GV aredetected from the reflected light of a laser spot LS illuminated on thegroove GV and, as the laser spot LS is moved along the recording track,the components of variations of the edge positions relative to the discradius direction are extracted to reproduce the wobble signal.

[0066] In the wobble signal, the address information (physical addressand other auxiliary information) for a recording position of therecording track is included modulated. So, with the present optical discdrive, the address information, for example, is demodulated from thewobble signal to effect e.g., address control at the time of datarecording and reproduction.

[0067] In the embodiments of the present invention, the optical discdesigned for groove recording is explained. However, the presentinvention may be applied not only to such optical disc for grooverecording but to an optical disc for land recording designed forrecording data on the land or to an optical disc for land-grooverecording designed for recording data on the land and the groove.

[0068] With the optical disc 1 of the present embodiment, two modulatingsystems are used for modulating the wobble signal with the addressinformation. One such system is the MSK (minimum shift keying)modulation system, while the other is a system in which even harmonicsare added to a sinusoidal carrier signal and in which the polarity ofthe even harmonics is changed depending on the sign of the data formodulation or the data to be modulated. That is, the other is a systemin which even harmonics of a sinusoidal carrier signal are added to thesinusoidal carrier signal and in which the polarity of the evenharmonics is changed depending on the sign of the data for modulation.The modulating system in which even harmonics are added to a sinusoidalcarrier signal and in which the polarity of the even harmonics ischanged depending on the sign of the data for modulation is termed HMW(harmonic wave) modulation.

[0069] In the present embodiment of the optical disc 1, shown in FIG. 3,a block comprised of a predetermined number of consecutive periods of asinusoidal carrier signal waveform of a predetermined frequency isformed, and a wobble signal having an MSK modulated portion and an HMWmodulated portion is generated in the block. In the MSK modulatedportion and in the HMW modulated portion, the MSK modulated addressinformation and the HMW modulated address information are inserted,respectively. That is, the MSK modulated address information and the HMWmodulated address information are inserted in different positions in theblock. One of the two sinusoidal carrier signals used in the MSKmodulation and the carrier signal of the HMW modulation correspond tothe aforementioned reference carrier signal. The MSK modulated portionand the HMW modulated portions are arranged at different positions inthe block, there being arranged a reference carrier signal of not lessthan one period of the reference carrier signal between the MSKmodulation portion and the HMW modulation portion.

[0070] Meanwhile, the portion of the block not subjected to datamodulation and in which only the frequency component of the referencecarrier signal is presented is termed a monotone wobble. The sinusoidalsignal used as the reference carrier signal is cos(ωt). One period ofthe reference carrier signal is termed one wobble period. The frequencyof the reference carrier signal is constant from the inner to the outerrims and is determined in relation to the linear velocity of movement ofthe laser spot along the recording track.

[0071] The methods for MSK modulation and HMW modulation are furtherexplained in detail.

[0072] 1-2 MSK Modulation

[0073] First, the modulation system of the address information employingthe MSK modulation system is explained.

[0074] The MSK modulation is the continuous-phase FSK (frequency shiftkeying) modulation with the modulation index of 0.5. In the FSKmodulation, the codes “0” and “1” of the data for modulation areassociated with two carrier signals, namely a carrier signal with afrequency f1 and a carrier signal with a frequency f2 for modulation,respectively. That is, the FSK modulation system is such a system inwhich a sinusoidal waveform with the frequency f1 is output if the datafor modulation is “0” and a sinusoidal waveform with the frequency f2 isoutput if the data for modulation is “1”. Moreover, in thecontinuous-phase FSK modulation, the two carrier signals arephase-continuous or same in phase at the code switching timing of thedata for modulation.

[0075] In this FSK modulation, the modulation index m is defined:Specifically, the modulation index m is defined by

m=|f1−f 2|T

[0076] where T is the rate of transmission of the data for modulation(1/time of the shortest code length). The continuous FSK modulation form=0.5 is termed the MSK modulation.

[0077] In the present optical disc 1, the shortest code length L of thedata for modulation, subjected to the MSK modulation, is equal to twowobble periods, as shown in FIGS. 4A and 4B. Meanwhile, the shortestcode length L of the data for modulation may be any optional lengthprovided that it is an integral number times the wobble period and notless than twice the wobble period. On the other hand, one of the twofrequencies used in MSK modulation is the same as the frequency of thereference carrier signal, with the other frequency being 1.5 times thefrequency of the reference carrier signal. That is, one of the signalwaveforms used for MSK modulation is cos(ωt) or −cos(wt), with the otherbeing cos(1.5ωt) or −cos(1.5ωt).

[0078] In inserting the data for modulation in the MSK modulation systeminto the wobble signal of the optical disc 1, a data stream of the datafor modulation is subjected to differential encoding processing in termsof a clock corresponding to the wobble period as a unit, as shown inFIG. 4C. That is, the stream of the data for modulation and delayed datadelayed by one period of the reference carrier signal are subjected todifferential encoding processing. The data resulting from thedifferential encoding processing is precode data.

[0079] This precode data is MSK modulated to generate an MSK stream. Asshown in FIG. 4D, the signal waveform of this MSK stream is the waveformof the same frequency as the reference carrier or cos(ωt) or itsinverted waveform −cos(ωt) if the precode data is “0”, while being thewaveform of the frequency 1.5 times the frequency of the referencecarrier or cos(1.5ωt) or its inverted waveform −cos(1.5ωt) if theprecode data is “1”. Thus, if the data string of the data for modulationis of a pattern “010” as shown in FIG. 4B, the signal waveform of theMSK stream is cos(ωt), cos(ωt), cos(1.5ωt), −cos(ωt), −cos(1.5ωt),cos(ωt), every wobble period, as shown in FIG. 4E.

[0080] In the present optical disc 1, the wobble signal is modulatedwith the address information by rendering the wobble signal theaforementioned MSK stream. So, the conversion of data from FIG. 4B toFIG. 4D is termed modulation and the conversion of data in the oppositedirection is termed demodulation.

[0081] If the data for modulation is differential-coded by way ofperforming the aforementioned MSK modulation, synchronous detection ofthe data for modulation becomes possible. The synchronous detectionbecomes possible for the following reason:

[0082] With the differential-coded data (precode data), the bit assertsitself (becomes “1”) at a code change point of the data for modulation.Since the code length of the data for modulation is selected to be notless than twice the wobble period, the reference carrier signal(cos(ωt)) or its inverted signal (−cos(ωt)) is necessarily inserted intothe latter half of the code length of the data for modulation. If thebit of the precode data is “1”, the waveform of a frequency 1.5 timesthat of the reference carrier signal is inserted and, at the codeswitching timing, the data before switching is in phase with that afterswitching. Therefore, the signal waveform inserted into the latter halfof the code length of the data for modulation is necessarily thewaveform of the reference carrier signal (cos(ωt)) if the data formodulation is “0”, whereas, if the data for modulation is “1”, thesignal waveform is necessarily its inverted signal (−cos(ωt)). Thesynchronous detection output is of a plus value if the data formodulation is in phase with the carrier signal, while being of a minusvalue if the data for modulation is inverted in phase. Thus, the datafor modulation can be demodulated if the MSK modulated signal describedabove is subjected to synchronous detection with the reference carriersignal.

[0083] Meanwhile, in the MSK modulation, modulation occurs in anin-phase state at the code switching positions. Thus, a delay isproduced until the synchronous detection signal is inverted in level.Therefore, if the signal MSK-modulated as described above is to bedemodulated, an integrating window of the synchronous detection outputis delayed by one-half the wobble period to produce a correctly detectedoutput.

[0084]FIG. 5 shows an MSK demodulating circuit for demodulating the datafor modulation from the above-mentioned MSK stream.

[0085] An MSK demodulating circuit 10 includes a PLL circuit 11, atiming generator (TG) 12, a multiplier 13, an integrator 14, asample-and-hold (SH) circuit 15 and a slicing circuit 16, as shown inFIG. 5.

[0086] The PLL circuit 11 is fed with a wobble signal (MSK modulatedstream). The PLL circuit 11 detects edge components from the inputwobble signal to generate wobble clocks synchronized with the referencecarrier signal (cos(ωt)). The so generated wobble clocks are sent to thetiming generator 12.

[0087] The timing generator 12 generates the reference carrier signal(cos(ωt)) synchronized with the input wobble signal. The timinggenerator 12 also generates a clear (CLR) signal and a hold (HOLD)signal from the wobble-clocks. The clear (CLR) signal is generated at atiming delayed by one-half wobble period from the leading edge of a dataclock of the data for modulation the minimum code length of which is twowobble periods. The hold signal (HOLD) is a signal generated at a timingdelayed one-half wobble period from the end edge of the data clock ofthe data for modulation. The reference carrier signal (cos(ωt)),generated by the timing generator 12, is sent to the multiplier 13. Thegenerated clear signal (CLR) is sent to the integrator 14, while thegenerated hold signal (HOLD) is sent to the sample-and-hold circuit 15.

[0088] The multiplier 13 multiplies the input wobble signal with thereference carrier signal (cos(ωt)) to execute synchronous detection. Thesynchronous detected output signal is sen to the integrator 14.

[0089] The integrator 14 integrates the synchronous detected signal bythe multiplier 34. Meanwhile, the integrator 14 clears the integratedvalue to zero at a generating timing of the clear signal (CLR) producedby the timing generator 12.

[0090] The sample-and-hold circuit 15 samples the integrated outputvalue of the integrator 14 at a generating timing of the hold signal(HOLD) produced by the timing generator 12 to hold the sampled valueuntil generation of the next hold signal (HOLD).

[0091] The slicing circuit 16 binary-encodes the value held by thesample-and-hold circuit 15, with-a point of origin (0) as a thresholdvalue, and inverts the sign of the encoded value to output the resultingsignal.

[0092] The output signal of the slicing circuit 16 becomes the data formodulation of the data for modulation.

[0093]FIGS. 6 and 7 show the wobble signal (MSK stream) generated on MSKmodulation of a data string “0100” as data for modulation and outputsignal waveforms of respective circuits of the MSK demodulating circuit10 when the wobble signal is fed to this MSK demodulating circuit 10. InFIGS. 6 and 7, the abscissa (n) denotes the period numbers of the wobbleperiods. FIG. 6 shows the input wobble signal (MSK stream) and thesynchronous detection output signal of the wobble signal (MSK×cos(ωt)).FIG. 7 shows an integrated output value of the synchronous detectedoutput signal, a sample-held value of the integrated output value andthe data for modulation output demodulated from the slicing circuit 16.Meanwhile, the data for modulation of the data for modulation, outputfrom the slicing circuit 16, is delayed because of the processing delaycaused in the integrator 14.

[0094] If the data for modulation is differential-encoded and subjectedto the above-described MSK-modulation, synchronous detection of the datafor modulation becomes possible, as described above.

[0095] In the present optical disc 1, the address information,MSK-modulated as described above, is formed into the wobble signal. ByMSK modulating the address information and by having the so modulatedaddress information formed into the wobble signal, the content ofharmonics in the wobble signal is decreased, thus enabling accurateaddress detection. Moreover, since the MSK modulated address informationis inserted in the monotone wobble, the crosstalk given to theneighboring track, may be reduced thus improving the S/N ratio. Inaddition, in the present optical disc 1, since the MSK data formodulation may be demodulated on synchronous detection, the wobblesignal can be demodulated correctly and readily.

[0096] 1-3 HMW Modulation

[0097] The modulation system for the address information, employing theHMW modulation system, is hereinafter explained.

[0098] The HMW modulation system is such a system in which signals ofeven harmonics are added to the sinusoidal carrier signal and in whichthe polarity of the even harmonics signal is varied depending on thesign of the data for modulation to modulate the digital code.

[0099] With the present optical disc 1, the carrier signal of the HMWmodulation is the signal of the same frequency and phase as those of thereference carrier signal (cos(ωt)) which is the carrier signal used inthe above-described MSK modulation. The even harmonics signals to beadded are sin(2(ωt) and −sin(2ωt) as second harmonics of the referencecarrier signal (cos(ωt)), with the amplitudes thereof being −12 dB withrespect to the amplitude of the reference carrier signal. The minimumcode length of the data for modulation is twice the wobble period(period of the reference carrier signal).

[0100] If the sign of the data for modulation is “1”, sin(2ωt) is addedto the carrier signal, whereas, if the sign of the data for modulationis “0”, −sin(2ωt) is added to the carrier signal, for modulation.

[0101]FIG. 8 shows the signal waveform in case the wobble signal ismodulated by the above-described system. FIG. 8A shows the signalwaveform of the reference carrier signal (cos(ωt)), while FIG. 8B showsthe signal waveform obtained on adding sin(2ωt) to the reference carriersignal (cos(ωt)), that is the signal waveform in case the data formodulation is “1”. FIG. 8C shows the signal waveform obtained on adding−sin(2ωt) to the reference carrier signal (cos(ωt)), that is the signalwaveform in case the data for modulation is “0”.

[0102] In the present optical disc 1, the harmonics signal added to thecarrier signal is second harmonics. However, any optional even harmonicsmay be added in place of the second harmonics. Moreover, although onlythe second harmonics are added in the present optical disc 1, pluralharmonics signals, such as second and fourth harmonics may be addedsimultaneously.

[0103] If the positive or negative even harmonics are added to thereference carrier signal, as described above, the data for modulationcan be demodulated, by synchronous detection with the harmonics signalsand by integration of the synchronous-detected output for the codelength time of the data for modulation.

[0104]FIG. 9 shows an HMW modulation circuit for demodulating the datafor modulation from the wobble signal HMW modulated as described above.

[0105] An HMW demodulating circuit 20 includes a PLL circuit 21, atiming generator (TG) 22, a multiplier 23, an integrator 24, asample-and-hold circuit (SH) 25 and a slicing circuit 26, as shown inFIG. 9.

[0106] The PLL circuit 21 is fed with a wobble signal (HMW modulatedstream). The PLL circuit 21 detects edge components from the inputwobble signal to generate wobble clocks synchronized with the referencecarrier signal (cos(ωt)). The so generated wobble clocks are sent to thetiming generator 22.

[0107] The timing generator 22 generates second harmonics signal(sin(2ωt)) synchronized with the input wobble signal. The timinggenerator 22 also generates a clear signal (CLR) and a hold signal(HOLD). The clear signal (CLR) is a signal generated at a timing of arising edge of a data clock of the data for modulation having two wobbleperiods as its minimum code length. The hold signal (HOLD) is a signalgenerated at the falling edge of the data clock of the data formodulation. The second harmonics (sin(2ωt)), produced by the timinggenerator 22, is sent to the multiplier 23. The clear signal (CLR)generated is routed to the integrator 24, while the hold signal (HOLD)generated is sent to the sample-and-hold circuit 25.

[0108] The multiplier 23 multiplies the input wobble signal with thesecond harmonics (sin(2ωt)) to perform synchronous detection. Thesynchronous-detected output signal is sent to the integrator 24.

[0109] The integrator 24 integrates the signal synchronous-detected bythe multiplier 23. Meanwhile, the integrator 24 clears the integratedvalue to zero at a generating timing of the clear signal (CLR) by thetiming generator 22.

[0110] The sample-and-hold circuit 25 samples the integrated outputvalue of the integrator 24 at a generating timing of the hold signal(HOLD) produced by the timing generator 22 to hold the sampled valueuntil generation of the next hold signal (HOLD).

[0111] The slicing circuit 26 binary-encodes the value held by thesample-and-hold circuit 25, with a point of origin (0) as a thresholdvalue, and outputs the resulting encoded signal.

[0112] The output signal of the slicing circuit 26 becomes the data formodulation of the data for modulation.

[0113] FIGS. 10 to 12 show a signal waveform used in HMW modulating adata string “1010” as data for modulation, a wobble signal generated onHMW modulation and output signal waveforms from respective circuits incase the wobble signal is fed to the HMW demodulating circuit 20. InFIGS. 10 to 12, the abscissa (n) denotes the period numbers of thewobble periods. FIG. 10 shows the reference carrier signal (cos(ωt)), adata string “1010” as data for modulation and second harmonics signalwaveforms (±sin(2ωt), −12 dB) generated in meeting with the data formodulation. FIG. 11 shows the generated wobble signal (HMW stream). FIG.12A shows the synchronous-detected output signal of the wobble signal(HMW×sin(2ωt)), whilst FIG. 12B shows an integrated output value of thesynchronous-detected output signal, a sample-held value of theintegrated output and data for modulation output from the slicingcircuit 26. Meanwhile, the data for modulation, output from the slicingcircuit 26, is delayed because of the first order delay caused in theintegrator 14.

[0114] If the data for modulation is differential-encoded andMSK-modulated as described above, synchronous detection of the data formodulation becomes possible.

[0115] In the present optical disc 1, the address information,HMW-modulated as described above, is formed into the wobble signal. ByHMW modulating the address information, and by having the so modulatedaddress information formed into the wobble signal, it is possible tolimit frequency components and the reduce high harmonics components. Theresult is that the S/N ratio of the demodulated output of the wobblesignal can be improved and addresses can be detected correctly.Moreover, the modulating circuit can be constructed by a carrier signalgenerating circuit, a circuit for generating its harmonics componentsand a circuit for summing the outputs of these circuits, and thus may besimpler in structure. Additionally, the high frequency components of thewobble signal can be reduced to facilitate cutting in molding an opticaldisc.

[0116] Since the HMW modulated address information is inserted into themonotone wobble, it is possible to reduce the crosstalk applied to theneighboring tracks to improve the S/N ratio. Moreover, in the presentoptical disc, since the HMW data for modulation can be demodulated onsynchronous detection, the wobble signal can be demodulated accuratelyand extremely readily.

[0117] 1-4 Sum

[0118] In the present embodiment of the optical disc, described above,the MSK modulation system and the HMW modulation system are used as themodulation systems for modulating the wobble signal with the addressinformation. In the present optical disc 1, one of the frequencies usedin the MSK modulation system and the carrier frequency used in the HMWmodulation are the sinusoidal signal of the same frequency (cos(ωt)).Moreover, the monotone wobble including only the carrier signal(cos(ωt)), and which is free of data for modulation, is provided betweenrespective modulated signals in the wobble signal.

[0119] In the above-described optical disc 1, there is no interferenceproduced between the signal of the frequency used in MSK modulation andthe harmonics used for HMW modulation, so that, in detection, therespective modulation components are not affected by counterpartmodulation components. Thus, the respective address information,recorded by the two modulation systems, can be detected reliably. Theresult is the improved accuracy in controlling e.g., the track positionsin recording and/or reproducing the optical disc.

[0120] If the address information recorded by MSK modulation is of thesame data contents as the address information recorded by HMWmodulation, the address information can be detected more reliably.

[0121] Moreover, in the present optical disc 1, since one of thefrequencies used in the MSK modulation system and the carrier frequencyused in the HMW modulation are the same frequency of the sinusoidalsignals (cos(ωt)), and the MSK modulation and the HMW modulation areapplied to different portions in the wobble signal, it is sufficient inmodulation if harmonics signals for HMW modulation are added to a wobbleposition of the MSK modulated wobble signal which is intended for HMWmodulation, thus assuring highly facilitated MSK and HMW modulations.Moreover, since the MSK modulation and the HMW modulation are applied todifferent portions in the wobble signal and at least one period of themonotone wobble is provided between the two modulations, it is possibleto realize more accurate disc manufacture and more reliable addressdemodulation.

[0122] 2. Instance of Application to DVR

[0123] An instance of application of the aforementioned address formatto a high density optical disc termed DVR (data and video recording) ishereinafter explained.

[0124] 2-1 Physical Characteristics of DVR Disc

[0125] First, typical physical parameters of a DVR disc, to which thepresent address format is applied, are explained. Meanwhile, thesephysical parameters are merely illustrative such that the wobble formatnow explained may also be applied to an optical disc of any othersuitable physical characteristics.

[0126] The DVR disc of the present embodiment is an optical disc forrecording data in accordance with the phase change system. The disc sizeis 120 mm in diameter, with the disc thickness being 1.2 mm.

[0127] The area on the disc is composed of a lead-in area, a programarea and a lead-out area, looking from the inner peripheral side. Theinformation area, made up of these areas, is formed at a diametricalposition ranging from. 44 mm to 117 mm.

[0128] For recording and/or reproduction, the so-called blue laser lightof 405 nm is used. The NA of a lens is 0.85, with the track pitch being0.30 μm, a channel bit length being 0.086 μm and a data bit length being0.13 μm. The average transfer rate of the user data is 35 Mbits/sec.

[0129] The user data capacity is 22.46 Gbytes.

[0130] Data recording is by a groove recording system. That is, a trackis formed at the outset on the disc by a groove, on which recording isto be made. This groove is wobbled to record the address information ofthe present disc.

[0131] 2-2 Format of Data for Recording and/or Reproduction

[0132] The error correction block (ECC block) of phase change data ofthe present embodiment of the DVR disc is 64 kbytes (304 bytes×248bytes), as shown in FIG. 13. This ECC block is made up of 304 rows by216 columns of data, and 304 rows by 32 columns of parity, with onesymbol being one byte. The parity is generated by long distanceReed-Solomon coding of LDC (248, 216, 33) of 304 rows by 216 columns ofdata with respect to the column direction.

[0133] Meanwhile, in the present embodiment of the DVR disc, therecording and/or reproducing unit of the phase change data may be 2 kbytes. In this case, recording and/or reproduction is performed with theaforementioned 64 kbytes of the error correction block, and datarewriting is performed on desired 2 k bytes of the error correctionblock.

[0134] Turning to the recording and/or reproducing unit of the presentembodiment of the DVR disc, the ECC block is an ECC block cluster of 156symbols by 496 frames, as shown in FIG. 14, and a one-frame link areafor e.g., PLL is appended to each of the leading and trailing sides ofthe ECC block cluster to form a sum total of 498 frames of the recordingand/or reproducing cluster. This recording and/or reproducing cluster istermed an RUB (recording unit block).

[0135] Each frame of each ECC block cluster is made up of data symbols,split in terms of 38 bytes as a unit, and Sync codes or BIS (burstsindicator subcode) inserted between the respective data symbols.Specifically, each frame is made up of a Sync code, a data symbol (38bytes), BIS, a data symbol (38 bytes), BIS, a data symbol (38 bytes),BIS, a data symbol (38 bytes), in this order, looking from the leadingside. The BIS and Sync codes may be used for discriminating burst errorsin data reproduction. That is, if the continuous Sync and BIS representsymbol errors, the 38 bytes of the data symbol, sandwiched by the Syncand BIS, corrupted with errors, is also deemed to be corrupted withburst errors, and pointer erasure correction is performed accordingly.

[0136] 2-3 Address Format

[0137] 2-3-1 Relationship between Data for Recording and/or Reproductionand Addresses

[0138] In the present address format, the sole RUB (498 frames) ismanaged by three address units (ADIP_(—)1, ADIP_(—)2 and ADIP_(—)3),recorded as wobble, as shown in FIG. 15. That is, a sole RUB is recordedfor these three address units.

[0139] In the present address format, the sole address unit is formed byan 8-bit sync part and. 75 bits of a data part, totaling at 83 bits. Inthe present address format, the reference carrier signal of the wobblesignal recorded on the pre-groove is the cosine signal (cos(ωt)), withone bit of the wobble signal being formed by 56 periods of the referencecarrier signal, as shown in FIG. 16. The ‘bit’ herein means one bit ofthe information represented by the wobble signal. Thus, the length ofone period of the reference carrier signal (one wobble period) is 69times one channel length of the phase change. The 56 periods of thereference carrier signal forming one bit is referred to below as a bitblock.

[0140] 2-3-2 Sync Part

[0141]FIG. 17 shows a bit configuration of the sync part in the addressunit. The sync part is a portion for identifying the leading end of anaddress unit and is made up of four, namely first to fourth sync blocks(sync block “1,” sync block “2,” sync block “3” and sync block “4”).Each sync block is formed by a monotone bit and a sync bit, totaling totwo bit blocks.

[0142] Turning to the signal waveform of the monotone bit, shown in FIG.18A, the first to third wobbles of the bit block made up of 56 wobblesrepresent a bit synchronization mark BM, with the fourth to 56th wobblesas from the synchronization mark BM being monotone wobbles (signalwaveform of the reference carrier signal (cos(ωt)).

[0143] The bit synchronization mark BM is a signal waveform obtained onMSK modulating the data for modulation of a predetermined code patterndesigned for discriminating the leading end of a bit block. That is,this bit synchronization mark BM is a signal waveform generated ondifferential encoding of data for modulation of a predetermined codepattern and assigning the frequency depending on the sign of thedifferential encoded data. Meanwhile, the minimum code length L of thedata for modulation is two wobble periods. In the present embodiment,the signal waveform obtained on MSK modulating the data for modulationwith one bit (two wobble periods) of “1” is recorded as the bitsynchronization mark BM. That is, this bit synchronization mark BM is asignal waveform continuous, in terms of a wobble period as a unit, as“cos(1.5ωt), −cos(ωt) and −cos(1.5ωt)”.

[0144] So, the monotone bit can be generated by generating data formodulation such as “10000 . . . 00”, with the code length being twowobble periods, and by MSK modulating this data for modulation, as shownin FIG. 18B.

[0145] It should be noted that the bit synchronization mark BM isinserted not only at the leading end of the monotone bit of the syncpart but also at the leading end of each of all bit blocks as nowexplained. Thus, during recording and/or reproduction, this bitsynchronization mark BM may be detected and synchronized forsynchronization of the bit blocks in the wobble signal, that issynchronization of the 56 wobble periods. Moreover the bitsynchronization mark BM may be used as a reference for specifying theinserting positions in the bit block of various signals for modulationas hereinafter explained.

[0146] In the signal waveform of the sync bit of the first sync block(sync “0” bit), the first to third wobbles of the 56 wobbles making up abit block represent the bit synchronization mark BM, and the 17th to19th wobbles and the 27th to 29th wobbles thereof represent MSKmodulation marks MM, with the waveform of the remaining wobbles beingall monotone wobbles, as shown in FIG. 19A.

[0147] In the signal waveform of the sync bit of the second sync block(sync “1” bit), the first to third wobbles of the 56 wobbles making up abit block represent the bit synchronization mark BM, and the 19th to21st wobbles and the 29th to 31st wobbles thereof represent MSKmodulation marks MM, with the waveform of the remaining wobbles beingall monotone wobbles, as shown in FIG. 20A.

[0148] In the signal waveform of the sync bit of the third sync block(sync “2” bit), the first to third wobbles of the 56 wobbles making up abit block represent the bit synchronization mark BM, and the 21st to23rd wobbles and the 31st to 33rd wobbles thereof represent MSKmodulation marks MM, with the waveform of the remaining wobbles beingall monotone wobbles, as shown in FIG. 21A.

[0149] In the signal waveform of the sync bit of the fourth sync block(sync “3” bit), the first to third wobbles of the 56 wobbles making up abit block represent the bit synchronization mark BM, and the 23rd to25th wobbles and the 33rd to 35th wobbles thereof represent MSKmodulation marks MM, with the waveform of the remaining wobbles beingall monotone wobbles, as shown in FIG. 22A.

[0150] Similarly to the bit synchronization mark BM, the MSK modulationmark MM is a signal waveform generated on MSK modulating the data formodulation of a predetermined code pattern. That is, this MSK modulationmark MM is a signal waveform generated on differential encoding of datafor modulation of a predetermined code pattern and on assigning thefrequency depending on the sign of the differential-encoded data.Meanwhile, the minimum code length L of the data for modulationcorresponds to two wobble periods. In the present instance, the signalwaveform, obtained on MSK modulating the data for modulation, having onebit, corresponding to two wobble periods, set to “1”, is recorded as theMSK modulation mark MM. That is, this MSK modulation mark MM is acontinuous waveform, composed of “cos(1.5ωt), −cos(ωt) and −cos(1.5ωt)”,in terms of one wobble period as a unit.

[0151] That is, the sync bit of the first sync block (sync “0” bit) canbe generated on generating a data stream shown in FIG. 19B (with thecode length being two wobble periods) and on MSK modulating the sogenerated data stream. Similarly, the sync bit of the second sync block(sync “1” bit), sync bit of the third sync block (sync “2” bit) and thesync bit of the fourth sync block (sync “2” bit) can be generated ongenerating the data stream shown in FIG. 20B and on MSK modulationthereof, on generating the data stream shown in FIG. 21B and on MSKmodulation thereof and on generating the data stream shown in FIG. 22Band on MSK modulation thereof, respectively.

[0152] Meanwhile, the sync bit insertion pattern to a bit block of twoMSK modulation marks MM is unique with respect to the insertion patternof the MSK modulation marks MM in the remaining bit blocks. Thus, duringrecording and/or reproduction, the address unit can be synchronized byMSK demodulating the wobble signals, verifying the insertion pattern ofthe MSK modulation marks MM in the bit block and by discriminating atleast one of the four sync bits, thereby achieving demodulation anddecoding of the data part as now explained.

[0153] 2-3-3 Data Part

[0154]FIG. 23 shows a bit configuration of the data part in the addressunit. The data part holds real data of the address information and ismade up of 15, namely the first to 15th ADIP blocks (ADIP block “1” toADIP block “15”). Each ADIP block is made up of one monotone bit andfour ADIP bits.

[0155] The signal waveform of the monotone bit is similar to that shownin FIG. 18.

[0156] The ADIP bit denotes one bit of real data. The signal waveform ischanged with code contents of the real data bit.

[0157] If the sign content, denoted by the ADIP bit, is “1”, the firstto third wobbles, the 13th to 15th wobbles and the 19th to 55th wobblesof the bit block, made up of 56 wobbles, become the bit synchronizationmark BM, MSK modulation mark MM and the modulation part of HMW “1”composed of the reference carrier signal (cos(ωt)) and sin(2ωt) addedthereto, respectively, with the waveform of the remaining wobbles beingall monotone wobbles. That is, the ADIP bit, the sign content of whichis “1”, can be generated by generating data for modulation such as“100000100 . . . 00” with the code length being two wobble periods, MSKmodulating the so generated data for modulation, as shown in FIG. 24B,and by adding sin(2ωt), with an amplitude equal to −12 dB, to the 19thto 55th wobbles of the MSK modulated signal waveform, as shown in FIG.24C.

[0158] If the sign content denoting the ADIP bit is “0”, the first tothird wobbles, the 15th to 17th wobbles and the 19th to 55th wobbles ofthe bit block, made up of 56 wobbles, become bit synchronization markBM, MSK modulation mark MM and the modulation part of HMW “0” composedof the reference carrier signal (cos(ωt)) and −sin(2ωt) added thereto,respectively, with the waveform of the remaining wobbles being allmonotone wobbles. That is, the ADIP bit, the sign content of which is“0”, can be generated by generating data for modulation such as“100000010 . . . 00” with the code length being two wobble periods, andMSK modulating the so generated data for modulation, as shown in FIG.25B, and by adding −sin(2ωt), with an amplitude equal to −12 dB, to the19th to 55th wobbles of the MSK modulated signal waveform, as shown inFIG. 25C.

[0159] The ADIP bit has its bit contents distinguished depending on theinserting positions of the MSK modulation mark MM. That is, if the MSKmodulation mark MM is inserted at the 13th to 15th wobbles, it indicatesa bit “1”, whereas, if the MSK modulation mark MM is inserted at the15th to 17th wobbles, it indicates a bit “0”. Moreover, the ADIP bitdenotes, by the HMW modulation, the same bit content as the bit contentrepresented by the inserting position of the MSK modulation mark MM.Therefore, the ADIP bit denotes the same bit contents for the twodifferent modulation systems, thus assuring reliable data decoding.

[0160]FIG. 26 shows the format of the address unit showing theabove-described sync and data parts synthesized together.

[0161] In the address format of the present optical disc 1, the bitsynchronization mark BM, the MSK modulation mark MM and the HMWmodulating part are arranged discretely in one address unit, as shown inFIG. 26. Between the modulated signal portions is arranged at least onewobble period of the monotone wobble. As a result, there no risk ofinterference between respective modulation signals, thus assuringreliable demodulation of respective signals.

[0162] 2-3-4 Contents of Address Information

[0163]FIG. 27 shows the contents of the address information representedby the ADIP bit in the data part. In one address unit, there arecontained 60 (4×15) ADIP bits, such that there are shown informationcontents of 60 bits for a data string. This 60-bit address informationis made up of a 3-bit layer information (Layer) indicating the layernumbers in case of multi-layered recording, a 19-bit RUB information(RUB) indicating the RUB address, 2-bit address number information(address number/RUB) indicating the numbers of the address units in theRUB, the 12-bit auxiliary information (Aux data) stating e.g., therecording conditions, such as recording patterns, and the 24-bit parityinformation (parity),% as shown in FIG. 27.

[0164] The 24-bit parity is the so-called nibble base Reed-Solomon code,having 4 bits as one symbol (RS(15, 9, 7)). Specifically, errorcorrection coding is performed with the code length of 15 nibbles, dataof 9 nibbles and parity of 6 nibbles, as shown in FIG. 28.

[0165] 2-4 Address Demodulating Circuit

[0166] An address demodulating circuit for demodulating the addressinformation from the DVR disc of the aforementioned address format ishereinafter explained.

[0167]FIG. 29 shows a block structure of an address demodulatingcircuit.

[0168] The address demodulating circuit 30 includes a PLL circuit 31, atiming generator for MSK 32, a multiplier for MSK 33, an integrator forMSK 34, a sample-and-hold circuit for MSK 35, a slicing circuit for MSK36, a sync decoder 37, an MSK address decoder 38, a timing generator forHMW 42, a multiplier for HMW 43, an integrator for HMW 44, asample-and-hold circuit for HMW 45, a slicing circuit for HMW 46 and anaddress decoder for HMW 47, as shown in FIG. 29.

[0169] The PLL circuit 31 is fed with the wobble signal reproduced fromthe DVR disc. The PLL circuit 31 detects edge components from the inputwobble signal to generate wobble clocks synchronized with the referencecarrier signal (cos(ωt)). The so generated wobble clocks are sent to thetiming generator for MSK 32 and to the timing generator for HMW 42.

[0170] The timing generator for MSK 32 generates the reference carriersignal (cos(ωt)) synchronized with the input wobble signal. The timinggenerator for MSK 32 also generates a clear signal (CLR) and a holdsignal (HOLD) from the wobble clocks. The clear signal (CLR) is such asignal generated at a timing delayed one-half wobble period as from theleading edge of the data clock of the data for modulation having theminimum code length equal to two wobble periods. The hold signal (HOLD)is such a signal generated at a timing delayed one-half wobble period asfrom the trailing edge of the data clock of the data for modulation. Thereference carrier signal (cos(ωt)), generated by the timing generatorfor MSK 32, is sent to the multiplier for MSK 33. The generated clearsignal (CLR) is sent to the integrator for MSK 34. The generated holdsignal (HOLD) is sent to the sample-and-hold circuit for MSK 35.

[0171] The multiplier for MSK 33 multiplies the input wobble signal withthe reference carrier signal (cos(ωt)) by way of performing synchronousdetection processing. The synchronous-detected output signal is sent tothe integrator for MSK 34.

[0172] The integrator for MSK 34 integrates the signalsynchronous-detected by the multiplier for MSK 33. Meanwhile, theintegrator for MSK 34 clears the integrated value to “0” at thegeneration timing of the clear signal (CLR) by the timing generator forHMW 42.

[0173] The sample-and-hold circuit for MSK 35 samples an integratedoutput value of the integrator for MSK 34, at a timing of generation ofthe hold signal (HOLD) by the timing generator for MSK 32, to hold thesampled value until occurrence of the next hold signal (HOLD).

[0174] The slicing circuit for MSK 36 binary-encodes the value held bythe sample-and-hold circuit for MSK 35, with the point of origin (0) asa threshold value, and inverts the sign of the binary-coded value tooutput the resulting signal.

[0175] The output signal of the slicing circuit for MSK 36 becomes anMSK data for modulation stream.

[0176] The sync decoder 37 detects a sync bit in the sync part from thebit pattern of the data for modulation output from the slicing circuitfor MSK 36. The sync decoder 37 synchronizes the address unit from thedetected sync bit. Based on the synchronization timing of the addressunit, the sync decoder 37 generates an MSK detection window, indicatingthe wobble position of the MSK data for modulation in the ADIP bit ofthe data part, and an HMW detection window indicating the wobbleposition of HMW data for modulation in the ADIP bit of the data part.The synchronization position timing of the address unit, detected fromthe sync bit, the timing of the MSK detection window and the timing ofthe HMW detection window, are shown in FIGS. 30A, 30B and 30C,respectively.

[0177] The sync decoder 37 sends the MSK detection window and the HMWdetection window to the MSK address decoder 38 and to the timinggenerator for HMW 42, respectively.

[0178] The MSK address decoder 38, fed with a demodulated stream outputfrom the slicing circuit for MSK 36, detects the inserting position ofthe MSK modulation mark MM in the ADIP bit of the data streamdemodulated based on the MSK detection window to check the contents ofthe sign represented by the ADIP bit. That is, if the insertion patternof the MSK modulation mark of the ADIP bit is a pattern shown in FIG. 24or a shown in FIG. 25, the contents of the sign are verified to be “1”or “0”, respectively. The bit string obtained from the results of checkis output as the MSK address information.

[0179] The timing generator for HMW 42 generates the second harmonics(sin(2ωt)), synchronized with the input wobble signal. The timinggenerator for HMW 42 generates a clear signal (CLR) and a hold signal(HOLD) from the HMW detection window. The clear signal (CLR) is a signalgenerated at a timing of the leading edge of the HMW detection window.The hold signal (HOLD) is a signal generated at a timing of the end edgeof the HMW detection window. The second harmonics (sin(2ωt)) generatedby the timing generator for HMW 42 is sent to the multiplier for HMW 43.The clear signal (CLR) generated is sent to the integrator for HMW 44.The hold signal (HOLD) generated is sent to the sample-and-hold circuitfor HMW 45.

[0180] The multiplier for HMW 43 multiplies the input wobble signal withthe second harmonics (sin(2ωt)) by way of performing synchronousdetection processing. The synchronous-detected output signal is sent tothe integrator for HMW 44.

[0181] The integrator for HMW 44 performs integrating processing on thesignal synchronous-detected by the multiplier for HMW 43. Thisintegrator for HMW 44 clears the integrated value to “0” at a timing ofgeneration of the clear signal (CLR) by the timing generator for HMW 42,and holds the sampled value until occurrence of the next hold signal(HOLD).

[0182] The sample-and-hold circuit for HMW 45 samples an integratedoutput value of the integrator for HMW 44 at a timing of generation ofthe hold signal (HOLD) by the timing generator for HMW 42, such as tohold the sampled value until occurrence of the next hold signal (HOLD).That is, the HMW data for modulation has 37 wobbles in one bit block, sothat, if the clear (HOLD) signal is generated at n=0, n being the numberof wobbles, as shown in FIG. 30D, the sample-and-hold circuit for HMW 45samples the integrated values at n=36, as shown in FIG. 30E.

[0183] The slicing circuit for HMW 46 binary-encodes the value held bythe sample-and-hold circuit for HMW 45, with the point of origin (0) asthreshold value, to output the resulting binary-coded value.

[0184] An output signal of the slicing circuit for HMW 46 becomes thedata for modulation stream.

[0185] The address decoder for HMW 47 verifies the contents of the coderepresented by each ADIP bit from the data for modulation stream. Thebit string obtained from the verified result is output as the HMWaddress information.

[0186]FIG. 31 shows the signal waveform when the ADIP bit with the codecontents “1” is HMW demodulated by the HMW address decoder 47. Theabscissa (n) of FIG. 31 shows the period numbers of the wobble periods.FIG. 31A shows the reference carrier signal (cos(ωt)), data formodulation having the code contents “1” and second harmonics signalwaveforms (sin(2ωt), −12 dB), generated in meeting with the data formodulation. FIG. 31B shows generated wobble signal. FIG. 31C shows asynchronous-detected output signal (HMW×sin(2ωt)) of the wobble signal,an integrated output value of the synchronous-detected output signal, asample-held value of the integrated output and the data for modulationoutput by the slicing circuit for HMW 46.

[0187]FIG. 32 shows the signal waveform when the ADIP bit with the codecontents “0” is HMW demodulated by the HMW address decoder 47. Theabscissa (n) of FIG. 32 shows the period numbers of the wobble periods.FIG. 32A shows the reference carrier signal (cos(ωt)), data formodulation having the code contents “1” and second harmonics signalwaveforms (−sin(2ωt), −12 dB) generated in meeting with the data formodulation. FIG. 32B shows generated wobble signal. FIG. 32C shows asynchronous-detected output signal (HMW×sin(2ωt)) of the wobble signal,an integrated output value of the synchronous-detected output signal, asample-held value of the integrated output and the data for modulationoutput by the slicing circuit for HMW 46.

[0188] As described above, the address decoder 47 detects thesynchronization information of the address unit recorded by the MSKmodulation and effects MSK demodulation and HMW demodulation based onthe detection timing.

[0189] 3. Illustrative Structure of Optical Disc Drive

[0190] An illustrative structure of an optical disc drive, configuredfor recording and/or reproducing data for a phase change optical disc,to which the above-described address format is applied, is nowexplained.

[0191]FIG. 33 shows a block diagram of the optical disc drive.

[0192] The optical disc 1, loaded on a turntable, is run in rotation bya spindle motor 61 at a constant linear velocity (CLV) at the time ofrecording and/or reproduction.

[0193] An optical head 62 includes a laser diode, as a laser lightsource, a photodetector for detecting the reflected light, an objectivelens for converging the laser light on the disc, and a bi-axial unit forholding the objective lens for movement in the tracking and focussingdirections.

[0194] A matrix circuit 63 generates playback signals, focussing errorsignals, tracking error signals and wobble signals (push-pull signals)from a signal detected by the photodetector of the optical head 62.

[0195] A laser driver 64 excites a laser diode in the optical head 62 toemit light.

[0196] A servo circuit 65 effects focussing servo control, trackingservo control and sled servo control, based on the focussing errorsignals, tracking error signals and the sled error signals, as detectedby the matrix circuit 63.

[0197] A spindle circuit 66 runs the spindle motor 61.

[0198] A read-write (RW) circuit 67 performs recording compensation onthe recording data during recording, while generating clocks from thereplay signals during reproduction to binary-encode the replay signalsbased on the data clocks to generate replay data.

[0199] A modulation/demodulation circuit 68 performsmodulation/demodulation processing, such as run length limitedmodulation/demodulation, on data for recording and/or reproduction.

[0200] An ECC encoder/decoder 69 performs ECC encoding or ECC decodingon the data for recording and/or reproduction.

[0201] A clock generator 60 generates clock timing signals from thewobble signal to send the so generated clock timing signals to theread-write circuit 67, a wobble demodulating circuit 51 and to anaddress decoder 52.

[0202] The demodulating circuit 51 demodulates data modulated into thewobble signal. The address decoder 52 decodes the address information ofthe optical disc 1 from the data for modulation of the demodulatingcircuit 51. The demodulating circuit 51 and the address decoder 52 maybe configured as shown for example in FIG. 29.

[0203] A system controller 53 controls the various components making upthe present optical disc drive 50.

[0204] In the above-described optical disc drive 50, recording and/orreproducing data and a control command are exchanged e.g., with an AVsystem 55.

[0205] To the above-described optical disc drive 50, a recording commandand, for example, recording data, such as a picture bit stream, such asMPEG2 picture bit stream, are sent from the AV system 55. The recordingdata, sent from the AV system 55, are ECC-blocked by an ECCencoder/decoder 69 and subsequently subjected to data modulation forrecording by the modulation/demodulation circuit 68. The systemcontroller 53 acquires the current address information from the addressdecoder 52 and, based on this address information, shifts the recordingposition for the optical disc 1 to a desired address. The read/writecircuit 52 performs recording compensation on the recording data andactuates the laser driver 44 at a clock timing generated by the clockgenerator 60 to record data on the optical disc 1.

[0206] The optical disc drive 50 is fed during reproduction with areplay command from the AV system 55. The system controller 53 acquiresthe current address information from the address decoder 52 and, basedon the so acquired address information, shifts the replay position forthe optical disc 1 to a desired address. The signal reproduced from theaddress are binary-coded by the read/write circuit 67 and demodulated bythe modulation/demodulation circuit 68. An ECC encoder/decoder 69 sendsthe MPEG2 picture bit stream, obtained on error correction on the datafor modulation, to the AV system 55.

[0207] 4. Manufacturing Method for Optical Disc

[0208] The manufacturing method for the optical disc, to which isapplied the above-described address format, is now explained.

[0209] The manufacturing process for an optical disc is roughlyclassified into a so-called master disc process (mastering process) anda disc forming process (replication process). The mastering process is aprocess up to the completion of a metal master disc (stamper) used inthe disc forming process, and the disc forming process is a process formass-producing optical discs, by way of duplication of the stamper, fromthe stamper.

[0210] In the mastering process, photoresist is coated on a polishedglass substrate to form a photosensitive film, which is then subjectedto cutting for forming pits or grooves by light exposure. During thecutting, pit cutting of forming pits or grooves in areas correspondingto embossed areas on the radially innermost side of the disc and wobblecutting of forming the wobbling grooves in an area corresponding to thegroove-forming area are performed. On completion of the cutting,predetermined processing, such as development, is performed, after whichthe information is transferred, such as by electrocasting, onto themetal surface, to form a stamper necessary for duplicating the discs.

[0211]FIG. 34 shows a cutting device for performing wobble cutting on amaster optical disc.

[0212] A cutting device 70 is made up of an optical unit 82 forirradiating a light beam on the substrate 81 coated with the photoresistfor cutting, a rotational driving unit 83 for rotational driving thesubstrate 81, and a signal processor 84 for converting input data intorecording signals and for controlling the optical unit 82 and therotational driving unit 83.

[0213] The optical unit 82 includes a laser light source 71, such asHe—Cd laser, and an optical modulator 72. The optical unit 82 isresponsive to a wobble signal stream generated by the signal processor84 to cut a pre-groove as it causes meandering of the laser beam emittedby the laser light source 71.

[0214] The rotational driving unit 83 runs the substrate 71 in rotation,so that the pre-groove will be formed spirally from the inner rim side,while causing the substrate 71 to be moved radially in controlledmanner.

[0215] The signal processor 84 includes, for example, an addressgenerator 73, an MSK modulator 74, an HMW modulator 75, an adder 76 anda reference clock generator 77.

[0216] The address generator 73 generates the address information forMSK modulating the pre-groove of the optical disc and the addressinformation for HMW modulating the pre-grooves of the optical disc tosend the address information so produced to an MSK modulator 74 and toan HMW modulator 75.

[0217] Based on reference clocks, generated by a reference clockgenerator 77, the MSK modulator 74 generates two frequencies, namelycos(ωt) and cos(1.5ωt). The MSK modulator 74 also generates, from theaddress information, a data stream at a predetermined timing position ofwhich is formed the data for modulation synchronized with the referenceclock. The MSK modulator 74 MSK modulates the data stream with the twofrequencies of cos(ωt) and cos(1.5ωt) to generate MSK modulated signals.In the portion of the data stream in which the address information isnot subjected to MSK modulation, the MSK modulator 74 generates a signalwith a waveform of cos(ωt) (monotone wobble).

[0218] Based on the reference clocks, generated by the reference clockgenerator 77, the HMW modulator 75 generates second harmonics(±sin(2ωt)), synchronized with cos(ωt) generated by the MSK modulator74. The HMW modulator 75 outputs the second harmonics at a timing ofrecording the address information by HMW modulation. This timingcorresponds to the monotone wobble free of the MSK modulation. At thistime, the HMW modulator 75 outputs +sin(2ωt) and −sin(2ωt) in aswitching fashion depending on the digital sign of the input addressinformation.

[0219] The adder 76 adds second harmonics signals, output from the HMWmodulator 75, to the MSK modulated signals output from the MSK modulator74.

[0220] The output signal of the adder 76 is sent as the wobble signalstream to the optical unit 82.

[0221] Thus, the cutting device 70 is able to record the wobble,modulated with the address information, on the optical disc, using twomodulating systems, namely the MSK modulation system and the HMWmodulating system.

[0222] Moreover, in the present cutting device 70, one of thefrequencies used in the MSK modulating system and the carrier frequencyused in the HMW modulation represent the sinusoidal wave signal of thesame frequency (cos(ωt)) as that used in the HMW modulation. In thewobble signal, there is provided a monotone wobble, free of modulatingdata and containing only the carrier signal (cos(ωt)), between thewobble signals.

[0223] In addition, in the present cutting device 70, one of thefrequencies used in the MSK modulation system and the carrier frequencyused in the HMW modulation represent the sinusoidal wave signal of thesame frequency (cos(ωt)). The MSK modulation and the HMW modulation areapplied to different portions in the wobble signal, and harmonicssignals are added to positions intended for HMW modulation forgenerating the modulated signal. Thus, a stream can be subjected to twomodulations extremely simply.

INDUSTRIAL UTILIZABILITY

[0224] In the disc-shaped recording medium according to the presentinvention, a first digital information MSK modulated using a firstsinusoidal signal of a predetermined frequency and using a secondsinusoidal signal of a frequency different from the predeterminedfrequency, and a second digital information modulated onto a sinusoidalcarrier signal by adding even harmonics signals to the sinusoidalcarrier signal and by changing the polarity of the harmonics signalsaccording to the second digital information (HMW modulated), are formedinto a wobble signal of the recording track.

[0225] With this disc-shaped recording medium according to the presentinvention, the information, such as address information, can beefficiently formed into the wobble component to improve the S/N ratio inreproducing the information thus formed into the wobble component.

[0226] The disc driving device according to the present invention, thewobble information demodulating means includes a first demodulating unitfor retrieving the first digital information which is MSK modulatedusing a first sinusoidal signal of a predetermined frequency and using asinusoidal signal of a frequency different from the predeterminedfrequency of the first sinusoidal signal and a second demodulating unitfor retrieving the second digital information which is modulated onto asinusoidal carrier signal by adding even harmonics signals to thesinusoidal carrier signal and by changing the polarity of the harmonicssignals according to the second digital information (HMW modulated).

[0227] With the disc driving device according to the present invention,the wobble signal can be demodulated with high S/N from the disc-shapedrecording medium in which the information such as address informationhas been efficiently formed into its wobble components.

[0228] In the method and apparatus for producing the disc according tothe present invention, the land and/or the groove of the disc-shapedrecording medium can be meanderingly produced depending on the wobblesignal into which have been formed a first digital information MSKmodulated using a first sinusoidal signal of a predetermined frequencyand using a second sinusoidal signal of a frequency different from thepredetermined frequency of the first sinusoidal signal, and a seconddigital information modulated onto a sinusoidal carrier signal by addingeven harmonics signals to the sinusoidal carrier signal and by changingthe polarity of the harmonics signals according to the second digitalinformation (HMW modulated).

[0229] With the apparatus for producing the disc, according to thepresent invention, such a disc-shaped recording medium can be producedin which e.g., the address information is efficiently formed into thewobble components and in which the information formed into the wobblecomponents can be reproduced with an improved S/N ratio.

1. A disc-shaped recording medium having a land and/or a groove formedthereon in a circling fashion for operating as a recording track, saidrecording track meandering depending on a wobble signal, wherein saidwobble signal comprises a first digital information MSK modulated usinga first sinusoidal signal of a predetermined frequency and using asecond sinusoidal signal of a frequency different from saidpredetermined frequency, and a second digital information modulated ontoa sinusoidal carrier signal by adding even harmonics signals to saidsinusoidal carrier signal and by changing the polarity of said harmonicssignals according to said second digital information (HMW modulated). 2.The disc-shaped recording medium according to claim 1 wherein thefrequency of the first sinusoidal signal used in said MSK modulation isthe same as the frequency of the carrier signal used in said HMWmodulation.
 3. The disc-shaped recording medium according to claim 2wherein at least the address information of said recording track iscontained in said first digital information and/or said second digitalinformation.
 4. The disc-shaped recording medium according to claim 3wherein the address information is recorded in terms of an address unitformed by a predetermined number of periods of said carrier signal as aunit; and wherein said first address information MSK modulated and thesecond address information HMW modulated are recorded at differentpositions in said address unit.
 5. The disc-shaped recording mediumaccording to claim 4 wherein at least not less than one period of saidcarrier signal is recorded between the MSK modulated first addressinformation and the HMW modulated second address information.
 6. Thedisc-shaped recording medium according to claim 4 wherein the MSKmodulated first address information and the HMW modulated second addressinformation represent the same information.
 7. The disc-shaped recordingmedium according to claim 1 wherein a spirally formed groove serves asthe recording track.
 8. The disc-shaped recording medium according toclaim 1 wherein said first digital information and the second digitalinformation contain the information of the same contents.
 9. Thedisc-shaped recording medium according to claim 1 wherein said firstdigital information is modulated such that data for modulation having acode length equal to an integral number not less than 2 times the periodof said first sinusoidal signal is differential-encoded with a period ofsaid first sinusoidal signal to produce differential encoded data havinga code length resulting from differential coding equal to one period ofsaid first sinusoidal signal, and such that said first and secondsinusoidal signals are selected depending on the sign of thedifferential encoded data.
 10. The disc-shaped recording mediumaccording to claim 1 wherein the frequency of said second sinusoidalsignal is {fraction (3/2)} times the frequency of the first sinusoidalsignal.
 11. The disc-shaped recording medium according to claim 1wherein, in said first digital information, an MSK modulation markobtained on MSK modulation of data for modulation of a predeterminedcode pattern is inserted into a bit block formed by a predeterminednumber of consecutive periods of said first sinusoidal signal, with theinserting position of said MSK modulation mark in said bit blockrepresenting the sign of the first digital information.
 12. Thedisc-shaped recording medium according to claim 11 wherein a bitsynchronization mark obtained on MSK modulation of data for modulationof a predetermined code pattern is inserted at the leading end of saidbit block.
 13. The disc-shaped recording medium according to claim 12wherein the data contents of the first digital information arerepresented by synthesizing the codes represented by respective bitblocks in one information unit which is formed by a plural number ofconsecutive bit blocks.
 14. The disc-shaped recording medium accordingto claim 13 wherein, in one or more leading bit block of saidinformation unit, an insertion pattern of an MSK modulation markobtained on MSK modulation of data for modulation of a predeterminedcode pattern is an inserting pattern unique with respect to other bitblocks.
 15. The disc-shaped recording medium according to claim 1wherein said second digital information is HMW modulated by adding −12dB harmonics signals to said sinusoidal carrier signal.
 16. Thedisc-shaped recording medium according to claim 1 wherein said seconddigital information is HMW modulated by adding second harmonics signalsof the sinusoidal carrier signal to said sinusoidal carrier signal. 17.A disc-shaped recording medium having a land and/or a groove formedthereon in a circling fashion for operating as a recording track, saidrecording track meandering depending on a wobble signal, wherein anaddress unit with the address information stated therein is formed insaid wobble signal as a predetermined data unit, said addressinformation comprising at least an address of the recording track, saidaddress unit is constructed to include at least one bit blockrepresenting bits forming said address information, and said at leastone block is formed in a waveform comprising a predetermined number ofconsecutive periods of a sinusoidal carrier signal by inserting a firstbit string MSK modulated using said sinusoidal carrier signal and usinga further sinusoidal signal of a frequency different from a frequency ofsaid sinusoidal carrier signal, and a second bit string modulated ontosaid sinusoidal carrier signal by adding even harmonics signals to saidsinusoidal carrier signal and by changing the polarity of said harmonicssignals according to said second bit string (HMW modulated).
 18. Thedisc-shaped recording medium according to claim 17 wherein said firstand second bit strings are inserted at different positions in said bitblock.
 19. The disc-shaped recording medium according to claim 18wherein there is at least one period of said carrier signal between saidfirst and second bit strings.
 20. The disc-shaped recording mediumaccording to claim 17 wherein said first and second bit stringsrepresent the same bit string.
 21. The disc-shaped recording mediumaccording to claim 17 wherein a bit synchronization mark obtained on MSKmodulation of data for modulation of a predetermined pattern is insertedat the leading end of said bit block.
 22. The disc-shaped recordingmedium according to claim 17 wherein said address unit comprises atleast one synchronization block having a waveform which is formed by apredetermined number of consecutive periods of the sinusoidal carriersignal, and an MSK modulation mark inserted into said waveform, said MSKmodulation mark having been obtained on MSK modulation of data formodulation of a predetermined code pattern, with an insertion pattern ofsaid MSK modulation mark being a unique insertion pattern.
 23. Thedisc-shaped recording medium according to claim 22 wherein saidsynchronization block is inserted in the leading part of the addressunit.
 24. The disc-shaped recording medium according to claim 17 whereinthe frequency of a sinusoidal signal used in MSK modulation is {fraction(3/2)} times the frequency of the carrier signal.
 25. The disc-shapedrecording medium according to claim 17 wherein the harmonics signalsused in HMW modulation are second harmonics signals having an amplitudeof −12 dB relative to the carrier signal.
 26. The disc-shaped recordingmedium according to claim 17 wherein said first-bit string isrepresented by an inserting position of the MSK modulation mark in saidbit block, said MSK modulation mark having been obtained on MSKmodulation of data for modulation of a predetermined bit pattern. 27.The disc-shaped recording medium according to claim 17 wherein saidfirst bit is modulated by differential-coding data for modulation,having a code length twice the period of said carrier signal, with theperiod of said carrier signal, to generate differential-coded datahaving a code length resulting from the differential coding equal to oneperiod of the carrier signal; with the frequency being selecteddepending on the sign of the differential-coded data
 28. A disc drivingdevice for recording and/or reproducing a disc-shaped recording medium,having a land and/or a groove formed thereon in a circling fashion foroperating as a recording track, said recording track meanderingdepending on a wobble signal said disc driving device comprising: wobbleinformation demodulating means for reproducing said wobble signal fromsaid disc-shaped recording medium and for demodulating said wobblesignal to retrieve the digital information contained in said wobblesignal; wherein said wobble information demodulating means includes: afirst demodulating unit for retrieving the first digital informationwhich is MSK modulated using a first sinusoidal signal of apredetermined frequency and using a sinusoidal signal of a frequencydifferent from the predetermined frequency of said first sinusoidalsignal; and a second demodulating unit for retrieving the second digitalinformation which is modulated onto a sinusoidal carrier signal byadding even harmonics signals to said sinusoidal carrier signal and bychanging the polarity of said harmonics signals according to said seconddigital information (HMW modulated).
 29. The disc driving deviceaccording to claim 28 comprising: control means for controlling therecording or reproducing position for said disc-shaped recording medium;said wobble information demodulating means demodulating the addressinformation of said recording track contained in the first digitalinformation and/or the second digital information; said control meanscontrolling the recording or the reproducing position for saiddisc-shaped recording medium based on said address information.
 30. Anapparatus for manufacturing a disc-shaped recording medium by forming aland and/or a groove in a circling fashion on a surface of a master discof a disc-shaped recording medium, said apparatus comprising: means forforming said land and/or groove in a meandering fashion depending on awobble signal including a first digital information MSK modulated usinga first sinusoidal signal of a predetermined frequency and using asecond sinusoidal signal of a frequency different from saidpredetermined frequency of said first sinusoidal signal, and a seconddigital information modulated onto a sinusoidal carrier signal by addingeven harmonics signals to said sinusoidal carrier signal and by changingthe polarity of said harmonics signals according to said second digitalinformation (HMW modulated).
 31. A method for manufacturing adisc-shaped recording medium by forming a land and/or a groove in acircling fashion on a surface of a master disc of a disc-shapedrecording medium, said method comprising the step of: forming said landand/or groove in a meandering fashion depending on a wobble signalincluding a first digital information MSK modulated using a firstsinusoidal signal of a predetermined frequency and using a secondsinusoidal signal of a frequency different from said predeterminedfrequency of said first sinusoidal signal, and a second digitalinformation modulated onto a sinusoidal carrier signal by adding evenharmonics signals to said sinusoidal carrier signal and by changing thepolarity of said harmonics signals according to said second digitalinformation (HMW modulated).